Needle Navigation Research Articles

Needle tracking in low-resolution ultrasound volumes using deep learning

PurposeClinical needle insertion into tissue, commonly assisted by 2D ultrasound imaging for real-time navigation, faces the challenge of precise needle and probe alignment to reduce out-of-plane movement. Recent studies investigate 3D ultrasound imaging together with deep learning to overcome this problem, focusing on acquiring high-resolution images to create optimal conditions for needle tip detection. However, high-resolution also requires a lot of time for image acquisition and processing, which limits the real-time capability. Therefore, we aim to maximize the US volume rate with the trade-off of low image resolution. We propose a deep learning approach to directly extract the 3D needle tip position from sparsely sampled US volumes.MethodsWe design an experimental setup with a robot inserting a needle into water and chicken liver tissue. In contrast to manual annotation, we assess the needle tip position from the known robot pose. During insertion, we acquire a large data set of low-resolution volumes using a 16 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 16 element matrix transducer with a volume rate of 4 Hz. We compare the performance of our deep learning approach with conventional needle segmentation.ResultsOur experiments in water and liver show that deep learning outperforms the conventional approach while achieving sub-millimeter accuracy. We achieve mean position errors of 0.54 mm in water and 1.54 mm in liver for deep learning.ConclusionOur study underlines the strengths of deep learning to predict the 3D needle positions from low-resolution ultrasound volumes. This is an important milestone for real-time needle navigation, simplifying the alignment of needle and ultrasound probe and enabling a 3D motion analysis.

Phantom study of augmented reality framework to assist epicardial punctures.

The objective of this study is to evaluate the accuracy of an augmented reality (AR) system in improving guidance, accuracy, and visualization during the subxiphoidal approach for epicardial ablation. An AR application was developed to project real-time needle trajectories and patient-specific 3D organs using the Hololens 2. Additionally, needle tracking was implemented to offer real-time feedback to the operator, facilitating needle navigation. The AR application was evaluated through three different experiments: examining overlay accuracy, assessing puncture accuracy, and performing pre-clinical evaluations on a phantom. The results of the overlay accuracy assessment for the AR system yielded . Additionally, the puncture accuracy utilizing the AR system yielded . During the pre-clinical evaluation on the phantom, needle puncture with AR guidance showed , whereas needle puncture without AR guidance showed . Overall, the AR platform has the potential to enhance the accuracy of percutaneous epicardial access for mapping and ablation of cardiac arrhythmias, thereby reducing complications and improving patient outcomes. The significance of this study lies in the potential of AR guidance to enhance the accuracy and safety of percutaneous epicardial access.

Autonomous Needle Navigation in Subretinal Injections via iOCT.

Subretinal injection is an effective method for direct delivery of therapeutic agents to treat prevalent subretinal diseases. Among the challenges for surgeons are physiological hand tremor, difficulty resolving single-micron scale depth perception, and lack of tactile feedback. The recent introduction of intraoperative Optical Coherence Tomography (iOCT) enables precise depth information during subretinal surgery. However, even when relying on iOCT, achieving the required micron-scale precision remains a significant surgical challenge. This work presents a robot-assisted workflow for high-precision autonomous needle navigation for subretinal injection. The workflow includes online registration between robot and iOCT coordinates; tool-tip localization in iOCT coordinates using a Convolutional Neural Network (CNN); and tool-tip planning and tracking system using real-time Model Predictive Control (MPC). The proposed workflow is validated using a silicone eye phantom and ex vivo porcine eyes. The experimental results demonstrate that the mean error to reach the user-defined target and the mean procedure duration are within an acceptable precision range. The proposed workflow achieves a 100% success rate for subretinal injection, while maintaining scleral forces at the scleral insertion point below 15mN throughout the navigation procedures.

Towards Autonomous Retinal Microsurgery Using RGB-D Images.

Retinal surgery is a challenging procedure requiring precise manipulation of the fragile retinal tissue, often at the scale of tens-of-micrometers. Its difficulty has motivated the development of robotic assistance platforms to enable precise motion, and more recently, novel sensors such as microscope integrated optical coherence tomography (OCT) for RGB-D view of the surgical workspace. The combination of these devices opens new possibilities for robotic automation of tasks such as subretinal injection (SI), a procedure that involves precise needle insertion into the retina for targeted drug delivery. Motivated by this opportunity, we develop a framework for autonomous needle navigation during SI. We develop a system which enables the surgeon to specify waypoint goals in the microscope and OCT views, and the system autonomously navigates the needle to the desired subretinal space in real-time. Our system integrates OCT and microscope images with convolutional neural networks (CNNs) to automatically segment the surgical tool and retinal tissue boundaries, and model predictive control that generates optimal trajectories that respect kinematic constraints to ensure patient safety. We validate our system by demonstrating 30 successful SI trials on pig eyes. Preliminary comparisons to a human operator in robot-assisted mode highlight the enhanced safety and performance of our system.

Wearable Mechatronic Ultrasound-integrated AR Navigation System for Lumbar Puncture Guidance.

As one of the most commonly performed spinal interventions in routine clinical practice, lumbar punctures are usually done with only hand palpation and trial-and-error. Failures can prolong procedure time and introduce complications such as cerebrospinal fluid leaks and headaches. Therefore, an effective needle insertion guidance method is desired. In this work, we present a complete lumbar puncture guidance system with the integration of (1) a wearable mechatronic ultrasound imaging device, (2) volume-reconstruction and bone surface estimation algorithms and (3) two alternative augmented reality user interfaces for needle guidance, including a HoloLens-based and a tablet-based solution. We conducted a quantitative evaluation of the end-to-end navigation accuracy, which shows that our system can achieve an overall needle navigation accuracy of 2.83 mm and 2.76 mm for the Tablet-based and the HoloLens-based solutions, respectively. In addition, we conducted a preliminary user study to qualitatively evaluate the effectiveness and ergonomics of our system on lumbar phantoms. The results show that users were able to successfully reach the target in an average of 1.12 and 1.14 needle insertion attempts for Tablet-based and HoloLens-based systems, respectively, exhibiting the potential to reduce the failure rates of lumbar puncture procedures with the proposed lumbar-puncture guidance.

Handheld interventional ultrasound/photoacoustic puncture needle navigation based on deep learning segmentation.

Interventional ultrasound (US) has challenges in accurate localization of the puncture needle due to intrinsic acoustic interferences, which lead to blurred, indistinct, and even invisible needles in handheld linear array transducer-based US navigation, especially the incorrect needle tip positioning. Photoacoustic (PA) imaging can provide complementary image contrast, without additional data acquisition. Herein, we proposed an internal illumination to solely light up the needle tip in PA imaging. Then deep-learning-based feature segmentation alleviates acoustic interferences, enhancing the needle shaft-tip visibility. Further, needle shaft-tip compensation aligned the needle shaft in US image and the needle tip in the PA image. The experiments on phantom, ex vivo chicken breast, preclinical radiofrequency ablation and in vivo biopsy of sentinel lymph nodes were piloted. The target registration error can reach the submillimeter level, achieving precise puncture needle tracking ability with in-plane US/PA navigation.

Real-Time Precision Needle Tracking for Gynecological Interstitial Brachytherapy: A Phantom Feasibility Study

To determine if an advanced needle navigation and real-time precision tracking system developed for prostate biopsies can be used for the purpose of real-time guidance of interstitial needles in modern image-guided gynecologic brachytherapy. An agarose gel pelvic phantom was previously designed using 3D Slicer and Autodesk Fusion360 to model an average uterus from a 50-patient dataset, a vaginal canal from KleenSpec (TM, Welch Allyn) speculum dimensions, and a rectum to accommodate a BK 8848 endocavity biplane ultrasound [US] probe. After manufacturing the phantom with a 7.2cm x 3.7cm x 4.4cm (LxWxH) uterus and an attached 2.7cm x 1.4cmx 1.7cm (LxWxH) focal HR-CTV target, the model was imaged using MRI. The uterus and HR-CTV were contoured on MRI to aid in registration with US and provide a target for needle placement. The tracking system with endorectal probe was then used to image the phantom. Ultrasound images from a 180-degree sweep were acquired and a 3D Ultrasound-based volume was generated. Using the commercially available system, the MRI was imported and an MRI-Ultrasound fusion performed based on the uterus contours and then refined using contour-based deformable registration. Three desired locations for needle placement were defined to test the ability of the system to guide needles at these locations: one in the most lateral aspect of the HRCTV, one at the HRCTV-uterus interface, and one inside the uterus. The needle tracking sleeve that was indexed to the probe was used in conjunction with the software interface to guide the 17-gauge titanium needle placement in real time. The distance between actual needle and the intended needle location was measured for each successful needle placement. When possible, needles were removed and reinserted at the same desired location to test the reproducibility of insertion under US guidance. Two of the three intended needles were successfully placed using real-time US guidance. The most lateral needle in the HRCTV was not inserted due to limitations of the phantom design, specifically inaccessibility to the agarose phantom through the phantom wall supports. The inserted needles were visible and tracked to the desired location within 0.6 mm (needle located at HRCTV-uterus interface), and 2.2 mm (needles inserted centrally in the uterus). For the target within the uterus, needles were reinserted at the same target of interest with a ∆ 0.15mm in greatest range between attempts. We have demonstrated a proof of concept in which existing technology for prostate biopsies can be utilized for the application of interstitial gynecologic brachytherapy with a high degree of fidelity. Ongoing modifications to our validation phantom and the tracking system are needed to allow for variations in uterine anatomy, more rigorous evaluation of reproducibility, and multi-catheter placement.

Does needle positioning with magnetic field induction improve central venous catheterization performance by novice learners?

The novel ultrasound magnetic needle navigation technique can visualize the entire needle and identify its projected trajectory. We hypothesized that this technique increases the first-attempt success rate of central venous puncture by novice learners compared with the conventional needle navigation technique. This prospective, randomized, controlled trial with a crossover design included 50 participants with limited prior experience in US-guided procedures. Participants were randomly assigned to novel or conventional technique groups and asked to perform central venous cannulation in a phantom task trainer. After the first successful attempt, participants were allocated to the other technique group. Although participants in the novel technique group had a higher first-attempt success rate than did those in the conventional technique group, this difference was not statistically significant (p = 0.17). The total number of attempts also did not significantly differ (p = 0.16). The conventional technique group had more needle redirections (p = 0.01) and a longer time to successful cannulation (p = 0.01). The number of adverse effects (p = 0.32) did not differ between groups. Participant confidence levels were higher in the novel technique group (p < 0.001). Magnetic needle navigation can reduce the number of needle redirections, shorten the time to successful cannulation, and increase confidence levels by novice learners for successful US-guided central venous access.

Autonomous Needle Navigation in Retinal Microsurgery: Evaluation in ex vivo Porcine Eyes.

Important challenges in retinal microsurgery include prolonged operating time, inadequate force feedback, and poor depth perception due to a constrained top-down view of the surgery. The introduction of robot-assisted technology could potentially deal with such challenges and improve the surgeon's performance. Motivated by such challenges, this work develops a strategy for autonomous needle navigation in retinal microsurgery aiming to achieve precise manipulation, reduced end-to-end surgery time, and enhanced safety. This is accomplished through real-time geometry estimation and chance-constrained Model Predictive Control (MPC) resulting in high positional accuracy while keeping scleral forces within a safe level. The robotic system is validated using both open-sky and intact (with lens and partial vitreous removal) ex vivo porcine eyes. The experimental results demonstrate that the generation of safe control trajectories is robust to small motions associated with head drift. The mean navigation time and scleral force for MPC navigation experiments are 7.208 s and 11.97 mN, which can be considered efficient and well within acceptable safe limits. The resulting mean errors along lateral directions of the retina are below 0.06 mm, which is below the typical hand tremor amplitude in retinal microsurgery.

Needle-Based Electrical Impedance Imaging Technology for Needle Navigation.

Needle insertion is a common procedure in modern healthcare practices, such as blood sampling, tissue biopsy, and cancer treatment. Various guidance systems have been developed to reduce the risk of incorrect needle positioning. While ultrasound imaging is considered the gold standard, it has limitations such as a lack of spatial resolution and subjective interpretation of 2D images. As an alternative to conventional imaging techniques, we have developed a needle-based electrical impedance imaging system. The system involves the classification of different tissue types using impedance measurements taken with a modified needle and the visualization in a MATLAB Graphical User Interface (GUI) based on the spatial sensitivity distribution of the needle. The needle was equipped with 12 stainless steel wire electrodes, and the sensitive volumes were determined using Finite Element Method (FEM) simulation. A k-Nearest Neighbors (k-NN) algorithm was used to classify different types of tissue phantoms with an average success rate of 70.56% for individual tissue phantoms. The results showed that the classification of the fat tissue phantom was the most successful (60 out of 60 attempts correct), while the success rate decreased for layered tissue structures. The measurement can be controlled in the GUI, and the identified tissues around the needle are displayed in 3D. The average latency between measurement and visualization was 112.1 ms. This work demonstrates the feasibility of using needle-based electrical impedance imaging as an alternative to conventional imaging techniques. Further improvements to the hardware and the algorithm as well as usability testing are required to evaluate the effectiveness of the needle navigation system.

Phantom-based assessment of motion and needle targeting accuracy of robotic devices for magnetic resonance imaging-guided needle biopsy.

The current study proposes simple methods for assessing the performance of robotic devices intended for Magnetic Resonance Imaging (MRI)-guided needle biopsy. In-house made agar-based breast phantoms containing biopsy targets served as the main tool in the evaluation process of an MRI compatible positioning device comprising a needle navigator. The motion accuracy of mechanical stages was assessed by calliper measurements. Laboratory evaluation of needle targeting included a repeatability phantom test and a laser-based method. The accuracy and repeatability of needle targeting was also assessed by MRI. The maximum error of linear motion for steps up to 10mm was 0.1mm. Needle navigation relative to the phantom and alignment with the various biopsy targets were performed successfully in both the laboratory and MRI settings. The proposed biopsy phantoms offered tissue-like signal in MRI and good haptic feedback during needle insertion. The proposed methods could be valuable in the process of validating the accuracy of MRI-guided biopsy robotic devices in both laboratory and real environments.

Needle Navigation; a New Era in the Interventional Pain Practice: A Narrative Review

Background: The hazardous effects of x-ray based technologies and shortcomings of other imaging systems like ultrasound have raised attention to create a new guiding system for interventional practice. After the introduction of virtual reality, the next challenge was how to implement it in the medical guiding systems. Medical engineering used registration aligned features of one imaging modality with real anatomical points and merged them into one single hybrid model. This augmented reality made the foundation and provided a level surface for the construction of every other new level. The next level was how to track a device in this augmented reality, which was accomplished with trackers and registration. To overcome the shortcomings of each imaging modality, the solution was fusion imaging, the combination of more than one modality to overcome the limitations of each. Nowadays, this fusion imaging plus needle tracking is the most sophisticated of navigational systems that interventionists work with. Despite clinical improvements in other medical fields like neurosurgery and urology, most of the work in the interventional pain practice has been done on phantom models and human cadavers, and there is still low experience in clinical studies about this new guiding system. Methods: The electronic search for this review included full text English article between 1990-2021 in PubMed and Google Scholar databases. The terms that have been searched are: “virtual reality”, “augmented reality”, “needle navigation”, “needle tracking”, and “fusion imaging”. Results: The navigation imaging guided system can be a practical, safe, efficient, reproducible, feasible guiding option for interventional pain procedure. Conclusions: The navigation based interventional injection is a new era in the interventional pain practice and can omit X-ray based hazardous.

3-D Path-Following Control for Steerable Needles With Fiber Bragg Gratings in Multi-Core Fibers.

In this study, a closed-loop, 3-D path-following controller for steerable needles is presented. The control loop is closed via the feedback from FBG-inscribed MCFs embedded within the needle. The nonlinear guidance law, which is a well-known approach for path-following control of aerial vehicles, is used as the basis for the guidance method. To handle needle-tissue interactions, we propose using Active Disturbance Rejection Control (ADRC) because of its robustness within hard-to-model environments. We investigate both linear and nonlinear ADRC, and validate the approach with a Programmable Bevel-tip Steerable Needle (PBN) in both phantom tissue and ex vivo brain, with some of the experiments involving moving targets. The mean, standard deviation, and maximum absolute position errors are observed to be 1.79 mm, 1.04 mm, and 5.84 mm, respectively, for 3-D, 120 mm deep, path-following experiments. MCFs with FBGs are a promising technology for autonomous steerable needle navigation, as demonstrated here on PBNs. FBGs in MCFs can be used to provide effective feedback in path-following controllers for steerable needles.

Using Ultrasonography to Improve Fluoroscopic Needle Navigation in PM&R Residents and Medical Students: A Randomized Study

Using Ultrasonography to Improve Fluoroscopic Needle Navigation in PM&R Residents and Medical Students: A Randomized Study

Using ultrasonography to improve fluoroscopic needle navigation in PM&R residents and medical students; a Randomised study

BackgroundFluoroscopy guided interventions are widely used procedures in the treatment of musculoskeletal conditions. Understanding the movement of the needle is part of a resident's initial training when performing these procedures. Needle navigation training is largely gained with fluoroscopy. ObjectiveThe purpose of this study is to determine whether the use of ultrasound training can lead to a decrease in time to reach a target under fluoroscopy. Methods32 medical students or residents. Exposure of one group of trainees to a practice session of needle navigation using ultrasound. The control group did not participate in ultrasound training. Time to reach the target during a fluoroscopy guided needle navigation test was measured in both groups. ResultsThe mean time to reach the target under fluoroscopy of the students unexposed to an ultrasound training (group 1 control group) was 183 ​s (standard deviation ​= ​160 ​s), while that after ultrasound training (group 2 experimental group) was 150,81 ​s (standard deviation ​= ​96 ​s) (p ​= ​0,483) ConclusionFluoroscopy needle navigation training was not improved by a 1-h group practice session with in-plane ultrasound needle navigation practice. Further studies need to be done with exposure for residents to a group practice session longer than 1-h

Oncological and urinary outcomes following low-dose-rate brachytherapy with a median follow-up of 11.8 years.

To examine the long-term oncological outcomes and urological morbidity of low-dose-rate prostate brachytherapy (LDRBT) monotherapy using live intraoperative dosimetry planning and an automated needle navigation delivery system for the treatment of men with low and intermediate-risk prostate cancer. A prospective database of 400 consecutive patients who underwent LDRBT between July 2003 and June 2015 was retrospectively reviewed to assess urinary side-effects and biochemical progression, based on the Phoenix definition and also a definition of a prostate-specific antigen (PSA) level of ≥0.2 μg/L. Minimum patient follow-up was 5.5 years. The median follow-up of the entire cohort was 11.8 years. The median (range) PSA level was 6.1 (0.9-17) μg/L and the median Gleason score was 3 + 4. The biochemical relapse-free survival (RFS; freedom from biochemical recurrence) based on the Phoenix definition was 85.8% (343/400). The RFS using a 'surgical' definition of a PSA level of <0.2 μg/L was 71% (284/400). Of the 297 men followed for ≥10 years, prostate cancer-specific survival (PCSS) was 98% (291/297). Post-LDRBT urethral stricture developed in 11 men (2.8%, 11/400). For men with ≥10 years of follow-up, 22 men (7.4%, 22/297) required a pad for either stress or urge urinary incontinence (UI). UI was identified in only 2.2% (one of 46) of men who had a bladder neck incision (BNI) before LDRBT. LDRBT is associated with excellent PCSS, with a median follow-up of 11.8 years. The risk of post-implantation urethral stricture and UI is low and a pre-implantation BNI for management of bladder outflow obstruction does not increase the risk of UI or urethral stricture.

Investigating uncertainty in augmented reality enhanced renal navigation using in vitro patient-specific tissue-mimicking phantoms.

To improve the outcome of minimally invasive renal interventions, traditional video-guided needle navigation can be enhanced by tracking the needle, guiding the needle using video imaging, and augmenting the surgical scene with pre-procedural images or models of the anatomy. In our previous work we studied, both through simulations and in vitro experiments, the uncertainty associated with the model-to-phantom registration, as well as the camera-tracker calibration and video-guided navigation. In this work, we characterize the overall navigation uncertainty using tissue emulating patient-specific kidney phantoms featuring both virtual and physical internal targets. Pre-procedural models of the kidney phantoms and internal targets are generated from cone-beam CT images, and are registered to their intra-operative physical counter-parts. The user then guides the needle insertion to reach the internal targets using video-based imaging augmented with a virtual representation of the needle tracked in real time. Following navigation, we acquire post-procedural cone-beam CT images of the phantoms and inserted needles. These images are used to determine the ground truth needle navigation accuracy (i.e., needle to target distance) against which the intra-operative navigation accuracy (i.e., intra-op needle tip to target distance) is assessed. We also explore a method to update the pre-procedural model to physical phantom registration intra-operatively using tracked video imaging, with the overall goal to improve overall navigation accuracy in the event of sub-optimal initial image-to-phantom registration. Our results showed a navigation error of less than 3.5 mm in gelatin phantoms and less than 6.5 mm in PVA phantoms. Following registration correction intra-operatively, we showed an overall improvement in navigation from roughly 6 mm RMS to approximately 2 mm RMS error, which is acceptable given the inherent tracking, 3D printing and phantom manufacturing limitations.

Exploring object and multi-target instrument tracking for AR-guided interventions

Abstract The rapid development of available hard- and software for computer-assisted or augmented reality (AR) guided interventions creates a need for fast and inexpensive prototyping environments. However, intraoperative tracking systems in particular represent a high cost threshold. Therefore, this work presents a low-cost tracking method based on a conventional RGB camera. Here, a combined approach of multiple image targets and 3D object target recognition is implemented. The system is evaluated with a systematic accuracy assessment analyzing a total of 385 3D positions. On average, a deviation of 15,69+-9,95 mm was measured. In addition, a prototypical AR-based needle navigation visualization was developed using Microsoft HoloLens 2. This system’s feasibility and usability was evaluated positively in a pilot study (n=3).

Evaluation of optical tracking and augmented reality for needle navigation in sacral nerve stimulation

Background and objectiveSacral nerve stimulation (SNS) is a minimally invasive procedure where an electrode lead is implanted through the sacral foramina to stimulate the nerve modulating colonic and urinary functions. One of the most crucial steps in SNS procedures is the placement of the tined lead close to the sacral nerve. However, needle insertion is very challenging for surgeons. Several x-ray projections are required to interpret the needle position correctly. In many cases, multiple punctures are needed, causing an increase in surgical time and patient's discomfort and pain. In this work we propose and evaluate two different navigation systems to guide electrode placement in SNS surgeries designed to reduce surgical time, minimize patient discomfort and improve surgical outcomes. MethodsWe developed, for the first alternative, an open-source navigation software to guide electrode placement by real-time needle tracking with an optical tracking system (OTS). In the second method, we present a smartphone-based AR application that displays virtual guidance elements directly on the affected area, using a 3D printed reference marker placed on the patient. This guidance facilitates needle insertion with a predefined trajectory. Both techniques were evaluated to determine which one obtained better results than the current surgical procedure. To compare the proposals with the clinical method, we developed an x-ray software tool that calculates a digitally reconstructed radiograph, simulating the fluoroscopy acquisitions during the procedure. Twelve physicians (inexperienced and experienced users) performed needle insertions through several specific targets to evaluate the alternative SNS guidance methods on a realistic patient-based phantom. ResultsWith each navigation solution, we observed that users took less average time to complete each insertion (36.83 s and 44.43 s for the OTS and AR methods, respectively) and needed fewer average punctures to reach the target (1.23 and 1.96 for the OTS and AR methods respectively) than following the standard clinical method (189.28 s and 3.65 punctures). ConclusionsTo conclude, we have shown two navigation alternatives that could improve surgical outcome by significantly reducing needle insertions, surgical time and patient's pain in SNS procedures. We believe that these solutions are feasible to train surgeons and even replace current SNS clinical procedures.

Cone Beam CT With Flat Panel Detector and Biplane Fluoroscopy-Guided Percutaneous Trigeminal Nerve Rhizotomy Using Three-Dimensional Needle Trajectory Planning.

Trigeminal-mediated pain disorders can be devastating for patients refractory to medical therapy. Gasserian ganglion blocks and percutaneous trigeminal rhizotomy have been used with success to treat these patients, however, serious complication risks include facial hematoma, cranial nerve palsy, and stroke. Cone beam CT, combined with fluoroscopy and needle navigation has been shown to decrease needle pass rates, procedure time, radiation exposure, and complications in multiple interventional radiology procedures, but hitherto has not been utilized for Gasserian ganglion interventions. Here, we present two cases of trigeminal-mediated pain successfully treated via cone beam CT combined fluoroscopy and needle navigation.